I vote for Synapse Wireless RF Engines. If you are talking sort distances through walls, http://www.futureelectronics.com/en/technologies/semiconductors/wireless-rf/rf-modules-solutions/802154-zigbee/Pages/2270387-RF100P86.aspx

With a little bit of python code, you can hook your sensors up to the RF Engine. The RF Engine take care of the mesh network so you dont have to. That way you have sensors connected to RF Engine. Rf Engine can calculate and transmit values if you want. OR you can use the RF Engines as wireless serial if you want. There is a lot of potential there.

If you need more range or lower power usage, go with something like:http://www.futureelectronics.com/en/technologies/semiconductors/wireless-rf/rf-modules-solutions/802154-zigbee/Pages/6469811-RF200PD1.aspx

The RF200 as 3 mile Line-of-sight range, walls will deteriorate the range, but they have plenty of range for your application.

For more information about the RF Engines:http://www.synapse-wireless.com/index.php?mainID=3&subID=3&type=product&prodID=3

I'm not affiliated with Synapse Wireless, just a mostly happy customer.